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<title>FatFs - disk_write</title>
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<div class="para func">
<h2>disk_write</h2>
<p>The disk_write writes sector(s) to the disk.</p>
<pre>
DRESULT disk_write (
  BYTE <span class="arg">drv</span>,         <span class="c">/* [IN] Physical drive number */</span>
  const BYTE* <span class="arg">buff</span>, <span class="c">/* [IN] Write data (may be non aligned) */</span>
  DWORD <span class="arg">sector</span>,     <span class="c">/* [IN] Sector number to write */</span>
  UINT <span class="arg">count</span>        <span class="c">/* [IN] Number of sectors to write */</span>
);
</pre>
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<div class="para arg">
<h4>Parameters</h4>
<dl class="par">
<dt>pdrv</dt>
<dd>Specifies the physical drive number.</dd>
<dt>buff</dt>
<dd>Pointer to the <em>byte array</em> to be written.</dd>
<dt>sector</dt>
<dd>Specifies the start sector number in logical block address (LBA).</dd>
<dt>count</dt>
<dd>Specifies the number of sectors to write. FatFs specifis 1 to 128. Generally, a multiple sector transfer request must not be split into single sector transactions to the device, or you will never get good write performance.</dd>
</dl>
</div>


<div class="para ret">
<h4>Return Values</h4>
<dl class="ret">
<dt>RES_OK (0)</dt>
<dd>The function succeeded.</dd>
<dt>RES_ERROR</dt>
<dd>Any hard error occured during the write operation and could not recover it.</dd>
<dt>RES_WRPRT</dt>
<dd>The medium is write protected.</dd>
<dt>RES_PARERR</dt>
<dd>Invalid parameter.</dd>
<dt>RES_NOTRDY</dt>
<dd>The disk drive has not been initialized.</dd>
</dl>
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<div class="para desc">
<h4>Description</h4>
<p>This function is not required in read only configuration. The specified memory address is not that always aligned to word boundary because the type of pointer is defined as <tt>BYTE</tt>. For more information, read <a href="dread.html">description in disk_read function</a>.</p>
<p><em>Application program MUST NOT call this function while FatFs is in use, or FAT structure on the volume can be corrapted.</em></p>
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